B27 positive diseases versus B27 negative diseases

[The role of HLA-B27 in the pathogenesis and diagnosis of axial spondyloarthritis : 50 years after discovery of the strong genetic association]

BACKGROUND

The association of the human lymphocyte antigen B27 (HLA-B27) with ankylosing spondylitis (AS), also now called axial spondylarthritis (axSpA), was first described 50 years ago.

OBJECTIVE

This article gives an overview of the available knowledge on the topic.

MATERIAL AND METHODS

This is a narrative review based on the experience of the authors.

RESULTS

The HLA-B27 is a member of the HLA class I family of genes of the major histocompatibility complex (MHC). The prevalence of HLA-B27 in the central European population is approximately 8 %, i.e., the vast majority of carriers of HLA-B27+ remain healthy. The frequency of HLA-B27 shows a decline from north to south. The HLA-B27 explains only 30 % of the genetic burden of axSpA. The prevalence of the disease correlates with the frequency of HLA-B27 in the population, i.e., there are geographic differences. Approximately 60-90 % of patients with axSpA worldwide are HLA-B27+. Some 200 subtypes of HLA-B27 can be differentiated using the polymerase chain reaction (PCR). In Thailand and Sardinia two subtypes were found that are not associated with axSpA. The physiological function of HLA class I molecules is the defence of the organism against microbes. Microbial peptides are presented to the immune system, which can be specifically attacked by CD8+ T‑cells. Genetic polymorphisms of the enzyme endoplasmic reticulum aminopeptidase 1 (ERAP1), which breaks down peptides in the endoplasmic reticulum, are associated only with HLA-B27+ diseases.

DISCUSSION

The pathogenesis of axSpA is unclear but a major hypothesis is that of the arthritogenic peptides. In this it is assumed that potentially pathogenic foreign or autologous peptides can be presented by HLA-B27. If nothing else, HLA-B27 plays an important role in the diagnosis, classification and determination of the severity of axSpA.

Fifty years after the discovery of the association of HLA B27 with ankylosing spondylitis

The human lymphocyte antigen B27 (HLA B27) is a member of the HLA class I family of genes in the major histocompatibility complex whose name goes back to its discovery in studies of transplanted tissue compatibility. Its prevalence in the mid-European population is about 8%. The association of HLA B27 alleles with ankylosing spondylitis (AS), a highly heritable disease, which is part of the spectrum of axial spondyloarthritis (axSpA), was discovered 50 years ago. HLA B27 explains less than 30% of the total genetic load. About 60%-90% of axSpA patients worldwide carry HLA B27. The prevalence of the disease is linked to the frequency of HLA B27 in the population which implies that there are relevant differences. Among the roughly 200 subtypes known there are two which are not disease associated. The function of HLA class I molecules is to present peptides to the immune system to defend the organism against microbes targeted by CD8+T cells. This is much supported by the role of the endoplasmic reticulum aminopeptidase 1 (ERAP 1) in AS, an enzyme that is responsible for the intracellular trimming of peptides, since polymorphisms of this gene are only associated with HLA-B27+ disease. The arthritogenic peptide hypothesis trying to explain the pathogenesis of AS is based on that very immune function assuming that also self peptides can be presented. HLA-B27 also plays an important role in classification, diagnosis and severitiy of axSpA.

Is a positive family history of spondyloarthritis relevant for diagnosing axial spondyloarthritis once HLA-B27 status is known?

Objectives

A positive family history (PFH) of spondyloarthritis, in particular a PFH of AS or acute anterior uveitis, is associated with HLA-B27 carriership in chronic back pain patients. As it is unknown, the study aimed to investigate if a PFH contributes to diagnosing axial spondyloarthritis (axSpA) once HLA-B27 status is known.

Methods

In axSpA-suspected patients from the Assessment of SpondyloArthritis international Society (ASAS), DEvenir des Spondyloarthropathies Indifférenciéés Récentes (DESIR) and SPondyloArthritis Caught Early (SPACE) cohorts, logistic regression analyses were performed with HLA-B27 status and PFH according to the ASAS definition (ASAS-PFH) as determinants and clinical axSpA diagnosis as outcome at baseline. Analyses were repeated with a PFH of AS or acute anterior uveitis.

Results

In total, 1818 patients suspected of axSpA were analysed (ASAS n = 594, DESIR n = 647, and SPACE n = 577). In patients from the ASAS, DESIR and SPACE cohorts, respectively 23%, 39% and 38% had an ASAS-PFH, 52%, 58% and 43% were HLA-B27 positive, and 62%, 47% and 54% were diagnosed with axSpA. HLA-B27 was independently associated with an axSpA diagnosis in each cohort but an ASAS-PFH was not [ASAS cohort: HLA-B27 odds ratio (OR): 6.9 (95% CI: 4.7, 10.2), ASAS-PFH OR: 0.9 (95% CI: 0.6, 1.4); DESIR: HLA-B27 OR: 2.1 (95% CI: 1.5, 2.9), ASAS-PFH OR: 1.0 (95% CI 0.7, 1.3); SPACE: HLA-B27 OR: 10.4 (95% CI: 6.9, 15.7), ASAS-PFH OR: 1.0 (95% CI: 0.7, 1.5)]. Similar negative results were found for PFH of AS and acute anterior uveitis.

Conclusion

In three independent cohorts with different ethnical backgrounds, ASAS, DESIR and SPACE, a PFH was not associated independently of HLA-B27 with a diagnosis of axSpA. This indicates that in the vast majority of patients presenting with back pain, a PFH does not contribute to the likelihood of an axSpA diagnosis if HLA-B27 status is known.

Chronic lymphocytic leukemia patients with HLA-B27 referred for allogeneic hematopoietic stem cell transplantation do not have worse outcomes: Results of a population-based case series analysis in British Columbia, Canada

Human leukocyte antigen B27 (HLA-B27), associated with spondyloarthritis, was suggested to be protective against chronic lymphocytic leukemia (CLL). It is hypothesized that HLA-B27 patients may have worse outcome in part related to their other comorbidities.

OBJECTIVES

We sought to compare the clinical characteristics and outcomes of CLL and small lymphocytic lymphoma (SLL) patients referred for allogeneic hematopoietic stem cell transplantation (allo-HSCT) based on their HLA-B27 status.

METHODS

This retrospective population-based case series analyzed CLL/SLL patients who were HLA-typed for potential allo-HSCT in British Columbia, Canada.

RESULTS

of 279 CLL/SLL patients referred for potential allo-HSCT, 34 patients were HLA-B27 positive. For HLA-B27 patients, median age at CLL diagnosis was 53.5 years (range, 27-67) and 71% were male. Seven patients had 11q deletion and nine patients had 17p deletion detected prior to first CLL therapy or at relapse. Eleven HLA-B27 patients received allo-HSCT. Two patients developed acute myeloid leukemia. One patient with ankylosing spondylitis had Richter's transformation prior to any CLL therapy. Spondyloarthritis-related disorders were diagnosed in 12 HLA-B27 patients but there was no temporal correlation with development of CLL. Overall survival (OS) and treatment-free survival (TFS) were not significantly different between HLA-B27 patients with or without spondyloarthritis-related disorders. There were no significant differences in clinical characteristics at CLL diagnosis or OS/TFS between HLA-B27 positive and negative patients referred for allo-HSCT.

CONCLUSIONS

HLA-B27 positivity does not appear to influence outcome for CLL/SLL patients referred for allo-HSCT. Further studies are needed to evaluate the clinical significance of HLA-B27 in a general CLL population.

Association of Inflammatory Bowel Disease and Acute Anterior Uveitis, but Not Psoriasis, With Disease Duration in Patients With Axial Spondyloarthritis: Results From Two Belgian Nationwide Axial Spondyloarthritis Cohorts

OBJECTIVE

To determine the link between extraarticular manifestations (EAMs) and baseline characteristics in patients with axial spondyloarthritis (SpA), and to define their potentially differential prognostic value in 2 large, independent Belgian axial SpA cohorts with distinct recruitment periods.

METHODS

Information on demographic and clinical characteristics and extraarticular manifestations (EAMs) was obtained from patients with axial SpA originating from the (Be)Giant (Belgian Inflammatory Arthritis and Spondylitis) cohort, which includes consecutive axial SpA patients whose data have been collected since 2010, and from the ASPECT (Ankylosing Spondylitis Patients Epidemiological Cross-sectional Trial) cohort, a Belgian registry of cross-sectional data collected between February 2004 and February 2005 from consecutive patients with ankylosing spondylitis (AS) or probable AS.

RESULTS

Among the 1,250 Belgian patients studied, disease duration was associated with risk of developing inflammatory bowel disease (IBD), with an increase in risk by 20% per 10 years of disease duration (relative risk [RR] 1.2, P = 0.026), and associated with risk of developing acute anterior uveitis, with an increase in risk by 30% per 10 years of disease duration (RR 1.3, P < 0.001). In the subgroup of 171 newly diagnosed patients with prospective follow-up data, higher mean C-reactive protein levels over time were demonstrated in those with acute anterior uveitis or IBD compared to those without EAMs or those with psoriasis alone (each P = 0.01).

CONCLUSION

The risk of developing acute anterior uveitis or IBD, but not psoriasis, in patients with axial SpA seems to increase with disease duration and appears to be linked to a higher cumulative exposure to inflammation, thus providing a possible explanation for the differential structural progression observed in those with axial SpA.

Role of Human Leukocyte Antigens (HLA) in Autoimmune Diseases

Since the discovery of HLA 60 years ago, it has contributed to the understanding of the immune system as well as of the pathogenesis of several diseases. Aside from its essential role in determining donor-recipient immune compatibility in organ transplantation, HLA genotyping is meanwhile performed routinely as part of the diagnostic work-up of certain autoimmune diseases. Considering the ability of HLA to influence thymic selection as well as peripheral anergy of T cells, its role in the pathogenesis of autoimmunity is understandable. The aim of this paper is to provide a brief overview of the role and current clinical relevance of HLA-B27 in spondyloarthritis and HLA-B51 in Behçet's disease as well as HLA-DQ2/DQ8 in celiac disease and HLA-DRB1 in rheumatoid arthritis and to discuss possible future implications.

Role of Human Leukocyte Antigens (HLA) in Autoimmune Diseases

The aim of this review is to provide a brief overview of the role and current clinical relevance of HLA-B27 in spondyloarthritis and HLA-B51 in Behcet's disease as well as HLA-DQ2/DQ8 in celiac disease and HLA-DRB1 in rheumatoid arthritis and to discuss possible future implications.

The early disease stage in axial spondylarthritis: results from the German Spondyloarthritis Inception Cohort

OBJECTIVE

Ankylosing spondylitis (AS) is diagnosed late, because radiographs of the sacroiliac joints often do not show definite sacroiliitis at the time of disease onset. The aim of this study was to investigate whether patients without definite radiographically defined sacroiliitis, referred to as nonradiographic axial spondylarthritis (SpA), are different from patients with AS with regard to clinical manifestations and disease activity measures. Moreover, we sought to identify determinants of the development of radiographic sacroiliitis.

METHODS

In a cross-sectional analysis of 462 patients, we compared 226 patients with nonradiographic axial SpA (symptom duration < or =5 years) and 236 patients with AS (symptom duration < or =10 years) who are participants in the German Spondyloarthritis Inception Cohort. Radiographs of the sacroiliac joints and the spine were assessed by 2 readers in a blinded manner. Logistic regression analysis was applied to identify parameters associated with structural damage.

RESULTS

The 2 groups did not differ in the frequency of HLA-B27 positivity, inflammatory back pain, arthritis, enthesitis, and uveitis and had similar levels of disease activity, using measures such as the Bath Ankylosing Spondylitis Disease Activity Index. In both groups, HLA-B27 positivity determined the age at disease onset. Male sex (adjusted odds ratio [OR] 2.38, 95% confidence interval [95% CI] 1.19-4.73 [P = 0.014]) and an elevated C-reactive protein (CRP) level (adjusted OR 1.85, 95% CI 0.96-3.56 [P = 0.066]) were associated with radiographic sacroiliitis. In patients with AS, male sex and an elevated CRP level were also associated with the presence of syndesmophytes.

CONCLUSION

Clinical manifestations and disease activity measures are highly comparable between patients with early nonradiographic axial SpA and those with early AS, suggesting that these 2 entities are part of the same disease. Male sex and an elevated CRP level are associated with structural damage on radiographs, whereas HLA-B27 positivity determines the age at disease onset.

Undifferentiated Spondyloarthropathy in Chinese Patients

BACKGROUND

Undifferentiated spondyloarthropathy (USpA) is a unique group in spondyloarthropathy (SpA). This study will investigate the clinical and laboratory characteristics of USpA in the Chinese population.

METHODS

Forty two patients with USpA were enrolled from our rheumatology outpatient facility in this retrospective study. SpA was diagnosed according to the European Spondyloarthropathy Study Group (ESSG) criteria. Patients were considered having USpA when they had SpA but did not meet the criteria for the diagnosis of ankylosing spondylitis (AS), Reiter's syndrome or reactive arthritis (ReA), psoriatic arthritis (PsA), and inflammatory bowel diseases (IBD)-related arthritis, etc. Laboratory tests included erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP), immunoglobulin A (IgA), and human leukocyte antigen B27 (HLA-B27).

RESULTS

Among the 42 USpA patients, the ratio of men to women was 1.47:1, and the age at onset was 32.33 +/- 10.83 years old. Approximately 61.9% of patients had peripheral arthritis, 30.95% had uveitis, and 64.29% had positive HLA-B27. Among these female USpA patients, compared to males, there is a trend of older age at disease onset, higher percentage of HLA-B27 positive, more peripheral arthritis and uveitis, longer disease duration, and higher level of ESR, and IgA and CRP in serum. The items reaching significant difference between males and females were longer disease duration (p < 0.001), higher level of ESR (p < 0.001), and serum IgA (p = 0.03). There was no significant difference in clinical and laboratory characteristics between HLA-B27-positive and -negative groups.

CONCLUSIONS

Studies on USpA patients have not been reported in the Chinese population. In this study, we demonstrate the unique demographic characteristics, clinical and laboratory data of USpA in the Chinese population. These findings should be confirmed by analyzing larger number of patients and longer time for further follow-up. Such studies are crucial to understand the pathogenesis of USpA and evaluate its prognosis.

Two forms of reactive arthritis?

Inflammatory arthritides developing after a distant infection have so far been called reactive or postinfectious, quite often depending on the microbial trigger and/or HLA-B27 status of the patient. For clarity, it is proposed that they all should be called reactive arthritis, which, according to the trigger, occurs as an HLA-B27 associated or non-associated form. In addition to the causative agents and HLA-B27, these two categories are also distinguished by other characteristics. Most important, HLA-B27 associated arthritis may occur identical to the Reiter's syndrome with accompanying ureteritis and/or conjunctivitis, whereas in the B27 non-associated form this has not been clearly described. Likewise, only the B27 associated form belongs to the group of spondyloarthropathies.

Radiologic diagnosis and pathology of the spondyloarthropathies

Five different subtypes of spondyloarthropathy (SpA) are now recognized. Clinical and radiologic involvement of the sacroiliac joint is an outstanding feature of the SpA, especially ankylosing spondylitis (AS). In this partly debilitating form of SpA a unique type of inflammatory axial involvement is observed which is characterized by inflammation and new bone formation at different spinal sites. In longstanding disease sacroiliitis, spondylitis and spondylodiscitis are easily recognized by conventional radiography and even better by computed tomography--especially when bony changes have already taken place. The advantage of dynamic magnetic resonance imaging (MRI) is to visualize morphologic changes and inflammation at the same time. This facilitates detection of sacroiliitis and spondylitis/spondylodiscitis at early time points. Hopefully, this will lead to other forms of therapy to prevent ankylosis of the spine. The origin of the granulation tissue infiltrating cartilage and bone in AS might be the synovium, the subchondrium or the bone marrow itself. T cells and macrophages seem to play an important role in this inflammatory process in which TNF-alpha is present in severe cases. The mechanisms responsible for the increased bone formation observed in the course of AS are unknown.

Bowel inflammation and the spondyloarthropathies

The concept of spondyloarthropathies gathers together a group of chronic diseases in which not only the locomotor system is involved but also other organs, especially the gastrointestinal tract. In humans, ileocolonoscopic studies demonstrated the presence of inflammatory gut lesions in all the diseases in the spondyloarthropathy group; their presence varied in the different diseases between 20% and 70%. The inflammation could be related to specific disease features in the spondyloarthropathies. Further research supports the hypothesis of subclinical inflammatory bowel disease in some patients with spondyloarthropathy, in which the locomotor inflammation was the only clinical manifestation. The link between gut inflammation and arthropathy has also been demonstrated in animal models, notably the human leukocyte antigen B27 transgenic rats. The temporal relationship between activity and severity of colonic involvement and flares of peripheral arthritis directs treatment of choice. For all forms of enterogenic arthropathies, nonsteroidal anti-inflammatory drugs remain the acute treatment form. Caution is in order, however, because of their possible harmful effects on intestinal integrity, permeability, and even on gut inflammation.

Prevalence of spondylarthropathies in HLA-B27 positive and negative blood donors

OBJECTIVE

To determine the overall prevalence of spondylarthropathy (SpA) among whites.

METHODS

To screen for SpA symptoms, such as inflammatory back pain (IBP), joint swelling, psoriasis, and uveitis, or a specific family history, questionnaires were mailed to 348 blood donors (174 HLA-B27 positive and 174 HLA-B27 negative). From the responding 273 persons (78%; 140 B27 positive, 133 B27 negative), 126 were selected for further evaluation based on the symptoms reported. Of this group, 90 persons agreed to undergo physical examination (71.4%; 46 B27 positive, 44 B27 negative). There was no difference between the B27-positive and -negative groups in terms of age (mean +/- SD 38.4 +/- 10 versus 39.5 +/- 11 years) and sex ratio (67% versus 68% were men). In addition, 58 donors (32 B27 positive, 26 B27 negative) agreed to undergo magnetic resonance imaging (MRI) of the sacroiliac joints. A diagnosis of SpA and ankylosing spondylitis (AS) was made according to the European Spondylarthropathy Study Group criteria and the New York criteria.

RESULTS

SpA was diagnosed in 20 persons: 19 of 140 B27-positive (13.6%) and 1 of 133 B27-negative (0.7%) subjects (15 male and 5 female). AS was diagnosed in 9 persons (7 male and 2 female; 45%), undifferentiated SpA (USpA) in 7 (5 male and 2 female; 35%), psoriatic arthritis (PsA) in 3 (2 male and 1 female; 15%), and chronic reactive arthritis (ReA; Reiter's syndrome) in 1 (male; 5%). On the basis of a B27 frequency of 9.3% among the population of Berlin (3.47 million persons), the estimated prevalence of SpA was 1.9%, AS was 0.86%, USpA was 0.67%, and PsA was 0.29%. The relative risk of developing SpA in B27-positive subjects was calculated as 20.7 (95% confidence interval 4.6-94.2; P = 0.001). Of 58 persons with IBP, sacroiliitis was detected by MRI in 15 of 32 B27-positive (46.9%) and 1 of 26 B27-negative (3.9%) subjects (P = 0.002). Four of these 16 donors did not fulfill diagnostic criteria for SpA.

CONCLUSION

With a calculated prevalence of 1.9%, spondylarthropathies are among the most frequent rheumatic diseases in the white population. HLA-B27 positive persons carry a 20-fold increased risk of developing SpA. AS and USpA are the most frequent SpA subtypes. Persons with IBP who are B27 positive have a 50% likelihood of having sacroiliitis.

Reactive arthritis in patients attending an urban sexually transmitted diseases clinic

OBJECTIVE

To assess the prevalence, clinical manifestations, associated genital infections, and HLA associations of reactive arthritis (ReA) among patients attending an urban sexually transmitted diseases (STD) clinic.

METHODS

Using a standardized questionnaire, 271 consecutive adults, primarily black, with possible or proven Chlamydia trachomatis genital infection were screened for symptoms of ReA. A followup questionnaire was administered 6 weeks later by mail. Patients who reported at least 1 symptom were evaluated by a rheumatologist. HLA-B typing was performed on patients with objective ReA features.

RESULTS

Nine of 217 patients (4.1%) with genital infection/inflammation had objective ReA features. Chlamydial or nongonococcal STD syndromes were diagnosed in 8 of these 9 patients (88%). Genital infection/inflammation was asymptomatic in 78% of patients with ReA features. HLA-B27 or other B7-cross-reactive group antigens were not associated with the occurrence of ReA.

CONCLUSION

Nongonococcal genital infections, often asymptomatic, can trigger a relatively mild ReA in a larger number of exposed patients than previously thought, irrespective of the individual's HLA status.

[Prognostic factors in early inflammatory arthritis]

Rheumatoid arthritis (RA) and spondylarthropathies are the most frequent chronic inflammatory arthritides. RA is a potentially severe disease which causes a functional handicap in nearly half the patients 10 years after the first clinical symptoms. However RA is a heterogenous disorder characterized by wide variations in clinical manifestations, disease course and response to therapy. No prognosis factor has been identified and universally accepted and validated. Markers of prognosis would be highly appreciated by clinicians who could then more closely adapt their management decisions to the disease potential. Clinical and biological data collected to date have provided a limited amount of information. Nevertheless, ESR, CRP and rheumatoid factor titer appeared to be the most powerful available indicators of prognosis at the early stage of the disease. Recent progress in molecular biology strongly suggests that genetic markers (HLA-DRB1 alleles) could be correlated with disease severity and it would appear possible to distinguish immunogenetically homogeneous subpopulations of patients with RA. Serum concentrations of specific cartilage and bone molecules reflecting tissue turnover could correlate to rate of joint destruction. Finally a combination of the most pertinent markers could determine a "score of severity" of the disease. In spondylarthropathies, limited information is available at present. The variables which were usually correlated with disease severity are: onset before 16 years of age, hip arthritis, ESR, limitation of lumbar spine, sausage-like finger or toe, oligoarthritis, poor efficacy of nonsteroidal antiinflammatory drugs and rapid evolution during the first 2 years. Genetic factors could also have prognosis value that should be clarified.

Course of gut inflammation in spondylarthropathies and therapeutic consequences

Gut inflammation plays a crucial role in the pathogenesis of spondylarthropathies (SpA) since ileocolonoscopic studies have demonstrated the presence of gut inflammation in different forms of this concept: in ankylosing spondylitis (AS) (60%), in enterogenic (90%) and urogenital reactive arthritis (20%), in undifferentiated SpA (65%), in the pauciarticular and axial forms of psoriatic arthritis (16%), in late onset pauciarticular juvenile chronic arthritis (80%) and in acute anterior uveitis (66%). The strong relationship between gut and joint inflammation was demonstrated by performing a second ileocolonoscopy: remission of the joint inflammation was always connected with a disappearance of gut inflammation, whereas persistence of locomotor inflammation was mostly associated with the persistence of gut inflammation. During further evolution 20% of the non-ankylosing spondylitis SpA patients can develop AS. About 6% of the total group SpA patients, in whom inflammatory bowel disease (IBD) was excluded, developed Crohn's disease 5 to 9 years later. All these patients initially presented with gut inflammation, which indicates that this finding has prognostic value. The high prevalence of evolution to IBD in SpA patients confirms the thesis that both disease entities bear common pathogenic mechanisms, and confirms the place of IBD in the concept of SPA. Sulphasalazine (SASP), a successful drug in the treatment of IBD, has demonstrated its effectiveness in the treatment of SpA. The beneficial effect of the drug in this disease entity could be due to its anti-inflammatory effect on the gut wall, by normalizing its permeability and by preventing the entrance of antigens through the defective gut wall. However, SASP could not prevent the evolution to IBD.

Pathogenesis of spondylarthropathies. Persistent bacterial antigen, autoimmunity, or both?

We have discussed partially mutually exclusive, partially overlapping models for the pathogenesis of the spondylarthropathies. Not all possibilities have been presented here; others are discussed elsewhere (77, 78). Furthermore, we have not addressed the issue of B27-negative spondylarthropathy. However, in our opinion, the key to understanding the pathogenesis of the spondylarthropathies lies in the interaction between the class I MHC molecule HLA-B27 and the T cell response. Although a T cell response driven by persisting bacterial antigen is still an attractive hypothesis, it does not explain all the known aspects of spondylarthropathy pathogenesis. The possibility of autoimmunity triggered by bacterial infection needs also to be considered, especially the new idea of HLA-B27-derived peptides presented by class II MHC molecules. The predominant involvement of joints is not easily explained in the case of autoimmunity. Cross-reactivity to joint-specific structures such as type II collagen (79) and/or bacteria inside the joint at the beginning of the immune response, with induction of local autoimmunity, might be involved. Most of the issues raised here could be tested by experiment, and we can expect to learn soon whether any of these models will explain the pathogenesis, or if we have to look further. The PCR technique will facilitate the search for bacteria not only in peripheral joints, but also now in sacroiliac biopsy samples from patients with AS and other spondylarthropathies. A prospective study on ReA in an endemic area should teach us more about predisposing factors (for example for Shigella-induced enteritis, which occurs in many parts of the world outside Europe and the US) (80).(ABSTRACT TRUNCATED AT 250 WORDS)

Outcomes of HLA-B27-positive and HLA-B27-negative acute anterior uveitis

PURPOSE

Outcomes of HLA-B27-positive and HLA-B27-negative acute anterior uveitis were assessed after a mean follow-up of nine years. Rheumatologic complications, in particular the presence and course of ankylosing spondylitis, were examined during the same period.

METHODS

A hospital-based prospective study of 119 patients with HLA-B27-positive and 35 patients with HLA-B27-negative acute anterior uveitis was performed. All patients underwent a complete ophthalmologic and rheumatologic examination, including sacroiliac x-rays, and were examined again nine years later.

RESULTS

No statistically significant differences in ocular complications and visual outcome were found between both patient groups with acute anterior uveitis after nine years. Posterior synechiae were observed in one half of the affected eyes. Blindness was infrequent. Rheumatologic complications, including ankylosing spondylitis, originally seen in one half of the HLA-B27-positive patients, were observed in two thirds of the patients nine years later, compared to only two of 35 HLA-B27-negative patients. When ankylosing spondylitis was evident at first examination no clinically significant deterioration was observed nine years later.

CONCLUSIONS

After nine years we observed an ocular outcome equal for both patient groups. A small percentage of affected eyes became blind. Rheumatologic complications occurred in 55 (72%) of 76 HLA-B27-positive males and in 24 (56%) of 43 HLA-B27-positive females with acute anterior uveitis. The rheumatologic complications had a good prognosis.

Spondylarthropathy and selective IgA deficiency

No serum IgA was detected in a young male patient suffering from spondylarthropathy (SpA) with bilateral sacroiliitis arthritis, enthesopathy and inflammatory low back pain, whose symptoms occurred in reaction to a sexually induced urethritis. After a period of several months in which the spondylarthropathy was active, disease activity came to a rest. Three years later no progression of the SpA was observed. This finding might be an indication that IgA is not involved in the pathogenesis of spondylarthropathy.

Factors involved in the pathogenesis of HLA-B27 associated arthritis

The role of HLA-B27 in the pathogenesis of ankylosing spondylitis (AS), reactive arthritides (ReA) like Reiter's syndrome (RS) and acute anterior uveitis in unknown. The prevalence of these diseases in B27 positive individuals is five times greater than in the general population. In B27 positive relatives of such patients the prevalence is another ten times greater. In those being HLA-B27/HLA-B60 the prevalence increases again three times. Outside B27 and B60 no other responsible genetic markers have been found, although other factors must play a role to explain the familial preponderance. Since there are no indications that familial exogenous factors are of importance, these are probably genetic. None of the seven subtypes of B27 seems to show a prevalence for these diseases although more studies are urgently needed. This means that probably the so called B pocket in the groove of HLA-B27 molecules, fixing the arginine at position 2 of the peptides which are presented to the receptors of cytotoxic T cells is of pathogenic importance. It is possible that such peptides are derived from or induced by intracellularly proliferating Gram negative bacteria. Indicating these peptides already as arthritogenic and/or uveitogenic is probably too simple. It seems probable that the pathogenetic role of HLA-B27 is that of a common pathway bridging various exogenous factors with several clinical pictures (Figure 1). AAU is mostly unilateral and not always attacking the same eye. Also in B27 associated joint diseases some joints are affected and others not.(ABSTRACT TRUNCATED AT 250 WORDS)

The prognostic value of HLA DR4 and B27 antigens in early rheumatoid arthritis

The prognostic significance of HLA DR4 and B27 antigens was investigated in a 3-year follow-up of 87 patients with early rheumatoid arthritis (RA). The frequencies of DR1, DR4 and also of B27 were increased and the frequencies of DR2, DR3 and DR7 decreased compared with the normal Finnish population. During the follow-up with antirheumatic treatment, a similar improvement in clinical variables and laboratory measure assessing disease activity was found in both DR4-positive and DR4-negative RA patients. Despite clinical improvement a fast radiological progression in peripheral joints was observed but the presence of DR4 or B27 had no impact on the progression of joint damage. In some patients cervical changes developed early in the course of RA but were not related to DR4 or B27 positivity. The earlier observation of increased prevalence of HLA B27 in the Finnish RA patients was confirmed but the presence of B27 did not modify the clinical picture of RA.

Immunoepidemiology of post-Salmonella reactive arthritis in a cohort of women

Following a foodborne outbreak of Salmonella dysentery in a group of 79 women and 4 men, 6 individuals were found to have reactive arthritis (ReA). None of the affected individuals had the classical genetic marker HLA B27 although 2 of the 6 had CREG antigens. IgA antibodies to the lipopolysaccharide of the causative organism, Salmonella heidelberg, were found to be elevated in those patients with active ReA compared to those with inactive ReA or those who had dysentery but did not develop ReA. The lymphocyte proliferative response to both PHA and the whole S. heidelberg organism was impaired in the patients with ReA (active or inactive) compared with the non-ReA patient controls. In this predominantly female outbreak of Salmonellosis, the development of ReA lacked an association with HLA class I antigens commonly recognized.

Differences in HLA-B27 positive and negative patients with ankylosing spondylitis: study of clinical disease activity and concentrations of serum IgA, C reactive protein, and haptoglobin

To find out whether disease activity and B27 status were associated with serum concentrations of IgA, C reactive protein (CRP), and haptoglobin in ankylosing spondylitis (AS) multivariate analysis of variance was used to study 101 patients with AS whose disease was clinically classified as active or inactive, and who were HLA-B27 typed. It was found that B27 and disease activity do interact significantly to affect the serum concentrations of IgA, CRP, and haptoglobin. When the 77 B27+ patients were examined, however, it was found that disease activity was significantly associated with serum concentrations IgA. In contrast, in the 24 B27- patients concentrations of serum IgA were significantly associated with disease activity, but not. These results emphasise the known difference between B27+ and B27- AS and suggest different pathogenic mechanisms in the two forms of AS.

Early antibiotic treatment of reactive arthritis associated with enteric infections: clinical and serological study

OBJECTIVE

To find out whether a 10-14 days' course of antibiotics early in the course of reactive arthritis associated with enteric infections could reduce the severity and duration of the disease and whether the antibody response in patients with reactive arthritis associated with yersinia infection differed between those treated and those not treated with the antibiotics.

DESIGN

Prospective multicentre trial in which patients were randomised to treatment or no treatment with antibiotics. Patients were seen at three and six weeks and three, six, nine, 12, and 18 months after their first visit.

SETTING

Departments of infectious diseases in three hospitals in Linköping, Malmö, and Stockholm, Sweden.

PATIENTS

40 Consecutive patients who had had symptoms of reactive arthritis associated with enteric infection for less than four weeks.

INTERVENTIONS

20 Patients were allocated to treatment with antibiotics and 20 patients did not receive antibiotics. All patients received non-steroidal anti-inflammatory drugs, and four also received intra-articular steroid injections after at least six weeks' observation.

MAIN OUTCOME MEASURES

Arthritic symptoms assessed clinically and by using Ritchies' index; blood measurements reflecting inflammatory activity; serum IgG, IgM, and IgA antibody titres; HLA tissue type.

RESULTS

No difference was observed concerning duration of arthritis, grade of inflammation, and number of joints affected between patients treated and those not treated with antibiotics. Furthermore, there was no significant difference between the two groups in erythrocyte sedimentation rate and haptoglobin, IgG, and IgA concentrations. All values had returned to normal within three months. No patient developed chronic arthritis, but sustained slight arthralgia occurred in three patients. The HLA-B27 antigen was found in 23 (58%) of the patients, and its presence did not affect clinical outcome. The IgG, IgM, and IgA antibody responses were similar in patients treated with antibiotics and those not treated.

CONCLUSION

Short term antibiotic treatment has no beneficial effect on the clinical outcome of reactive arthritis associated with enteric infection.

Ophthalmological significance of HLA associated uveitis

The association between HLA-A29 and birdshot chorioretinopathy is the strongest association between HLA and disease ever described. The determination of HLA-A29 is therefore of diagnostic significance. The association between HLA-B27 and acute anterior uveitis (AAU) is much weaker. However, it is evident that B27+ AAU is clinically different from B27-AAU. Half of the B27+AAU patients have or will have ankylosing spondylitis or Reiter's syndrome. The determination of HLA-B27 is therefore of clinical significance and should be determined in each case of AAU. The B27+ patients should be referred to a rheumatologist. The determination of HLA-Bw51 is of limited but significant diagnostic value for the diagnosis of Behçet's disease in countries around the Mediterranean Sea or Japan. In Northern Europe HLA-Bw51 determination will not give much practical information. The structure and function of HLA class I molecules is now known. It is probable that HLA-A29 and HLA-B27 molecules are directly involved in the pathogenesis of respectively birdshot chorioretinopathy and AAU.

HLA and uveitis

The association between HLA-A29 and birdshot chorioretinopathy is the strongest of all associations between HLA and disease. Determination of HLA-A29 is even of diagnostic significance. The association between HLA-B27 and acute anterior uveitis (AAU) is much weaker, but B27 positive AAU may be considered as a distinct clinical entity. B27 positive patients with AAU should be referred to a rheumatologist, because half of these patients have ankylosing spondylitis or Reiter's syndrome. The determination of HLA-Bw51 is of limited but significant diagnostic value for the diagnosis of Behçet's disease. The present article shows how HLA determinations can serve as diagnostic tests. It is explained how the sensitivity and specificity of such tests can be used to calculate the influence of positive or negative results on the probability of the diagnosis. The structure and function of HLA class I molecules is now known to a great extent. This may lead to a better understanding of the pathogenic role of HLA-A29, HLA-B27, HLA-Bw51 and other HLA molecules which are associated with uveitis.

HLA-B27 and acute anterior uveitis

This article reviews the ophthalmological significance of the association between HLA-B27 and acute anterior uveitis (AAU). HLA-B27 determination should be performed in all cases of acute anterior uveitis (AAU), since B27+ AAU is a distinct kind of uveitis. All B27+ AAU patients have to be referred to a rheumatologist because half of these patients has ankylosing spondylitis or Reiter's syndrome. The structure and physiological role of HLA-class I molecules is now known. It is probable that the role of HLA-B27 in the pathogenesis of AAU will be revealed in the coming years.

HLA-B27 is necessary but not sufficient

It is discussed why some, but not all HLA-B27-positive persons get disease when triggered by certain infections. The conclusions are that a possible modifying gene may be found on the other HLA haplotype or outside the HLA complex. Given an epidemic infection afflicting a family, it is the possible differences of other environmental factors which may be of interest, not a further description of the infection initially recognized. The familial clustering of disease is based upon modifying genetic factor(s) and/or environmental factor(s) shared by the family members. Timing of the environmental factors may be instrumental. Penetrance of genetic predisposition may also depend on coincidence of randomly occurring environmental factors.

Serum levels of beta 2-microglobulin in HLA-B27+ patients with acute anterior uveitis and ankylosing spondylitis

Serum levels of beta 2m were monitored in 89 HLA-B27+ patients with acute anterior uveitis (AAU) and in their first degree relatives. Serum levels of both patients and relatives were not elevated compared to sex and age matched controls. Neither the activity of the uveitis, nor the presence or absence of ankylosing spondylitis (AS), correlated with beta 2m levels. On the contrary, 6 of 27 HLA-B27- patients with AAU had elevated serum levels of beta 2m. These findings do not confirm previous reports which showed elevated serum levels of beta 2m in patients with AS. A possible role for beta 2m in the pathogenesis of HLA-B27+ AAU and AS is discussed.